(a) Field of the Invention
The present invention relates to a power supply system for charging a battery of a vehicle, and method thereof. More particularly, the present invention relates to a power supply system for charging a battery for an electric vehicle and a plug-in hybrid vehicle, and a method thereof.
(b) Description of the Related Art
Compared to a general internal combustion engine vehicle, an electric vehicle (EV) and a hybrid electric vehicle (HEV), which are environmentally friendly vehicles, are operated by a motor using battery power. Since environmentally friendly vehicles are operated by a motor, a high voltage large capacity battery (hereinafter referred to as a “high voltage battery”) is mounted within the vehicle and a plug-in charging method may be used to charge the high voltage battery using an external commercial power supply. In addition, an on-board charger is provided in the environmentally-friendly vehicles. The on-board charger rectifies external commercial power for offering plug-in charging and charges the high voltage battery.
Meanwhile, a 12 V auxiliary battery supplies power to operate the on-board charger when plug-in charging of the environmentally friendly vehicles is started. In particular, the auxiliary battery is generally used to start environmentally friendly vehicles or supply power to an electric field load. When the auxiliary battery is being continuously used, the auxiliary battery may be completely discharged, and thus it the environmentally friendly vehicle may not be started.
Furthermore, a known apparatus for charging a battery may include an auxiliary voltage charging unit that charges an auxiliary battery in addition to a high voltage charging unit that charges a high voltage battery, and separately converts AC power into a high voltage and an auxiliary voltage. However, charging efficiency may decrease due to frequent charging and discharging of the high voltage battery and the auxiliary battery.
The above information disclosed in this section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.